John
what do you consider a tapered leader? the ones i use have no steps. I have used Froghair, Riverge, Orvis Super strong, Hardy Co-poly and Rio Powerflex all with no problems. I am currently using Trouthunter leaders as they are the only ones i can still get that are 14ft. I can get a 3x taper into a 5wt no problem, so you shouldn't have any problems. usually i fish 5x and 4x ,14ft tapers.
I am using tapered leaders and not polyleaders
i doubt a polyleader would work, far too thick.
Hope that helps
Sandy